The Economist has a piece on how low social status is bad for your health, and why.  Which I find fascinating.

But this bit is really crazy:

Epigenetics—currently one of molecular biology’s hottest topics—is a process by which genes are activated or deactivated by the presence or absence of chemical structures called methyl and acetyl groups. Dr Tung and Dr Gilad found that methylation patterns were systematically different in high- and low-ranking animals. Crucially, these changes are generally passed on to the daughter cells produced when a cell divides, and are thus perpetuated throughout an animal’s life. To the extent that epigenetic marking is involved in creating social status, then, status may be being maintained by the animal’s cells as they replicate.

When reading history, I've always wondered why lowly peasants put up with their lot in life while defeated kings (and their offspring) manage to get back up on their thrones (or new thrones) without much protest.  This epigenetic marking stuff goes a long way towards explaining why (along with cultural norms, illiteracy, and such).